import pygame

class Ship():
	
	def __init__(self,ai_settings,screen):
		"""初始化飞船并设置其初始化设置"""
		self.screen = screen
		self.ai_settings = ai_settings
	
		# 加载飞船图像并获取其外接矩形
		self.image = pygame.image.load('images/ship.bmp')
		self.rect = self.image.get_rect()
		self.screen_rect = screen.get_rect()		

		# 将每首新飞船放在屏幕底部中央
		self.rect.centerx = self.screen_rect.centerx
		self.rect.bottom = self.screen_rect.bottom
	
		# 在飞船的属性center中存储小值
		self.center = float(self.rect.centerx)

		#移动标志
		self.moving_right = False
		self.moving_left = False

	def update(self):
		"""根据移动标志调整飞机位置"""
		#更新飞船的center值，而不是rect
		if self.moving_right and self.rect.right < self.screen_rect.right:
			self.center += self.ai_settings.ship_speed_factor
			# self.rect.centerx += self.ai_settings.ship_speed_factor
		elif self.moving_left and self.rect.left > 0:
			# self.rect.centerx -= self.ai_settings.ship_speed_factor
			self.center -= self.ai_settings.ship_speed_factor
		#根绝self.centerx更新rect对象
		self.rect.centerx = self.center

	def blitme(self):
		"""在指定的位置绘制飞船"""
		self.screen.blit(self.image, self.rect)
